Switchgear with overmolded dielectric material

ABSTRACT

A switchgear apparatus configured for operation at voltages up to 72.5 kV includes a vacuum interrupter assembly including a vacuum bottle having an upper portion and a lower potion, a sleeve surrounding the vacuum bottle, a dielectric material surrounding the sleeve, a first terminal electrically coupled to the upper portion of the vacuum interrupter assembly, and an interchange coupled to a lower portion of the vacuum interrupter assembly. The dielectric material is molded around the sleeve and around at least a portion of the first terminal or the interchange. In some embodiments, the sleeve is molded around the vacuum bottle. In other embodiments, the sleeve may be otherwise positioned (i.e., by sliding a pre-formed sleeve) around the vacuum bottle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to co-pending U.S. Provisional PatentApplication No. 62/839,278, filed on Apr. 26, 2019, and to co-pendingU.S. Provisional Patent Application No. 62/889,577, filed on Sep. 12,2019, the entire contents of both of which are incorporated herein byreference.

FIELD OF THE DISCLOSURE

The present disclosure relates to solid dielectric switchgear, and moreparticularly to reclosers.

BACKGROUND OF THE DISCLOSURE

Reclosers are switchgear that provide line protection, for example, onoverhead electrical power lines and/or substations and serve to segmentthe circuits into smaller sections, reducing the number of potentiallyimpacted customers in the event of a short circuit. Previously,reclosers were controlled using hydraulics. More recently, soliddielectric reclosers have been developed for use at voltages up to 38kV. Solid dielectric reclosers may be paired with electronic controldevices to provide automation and “smart” recloser functionality.

SUMMARY OF THE DISCLOSURE

A need exists for fault protection and circuit segmentation in powertransmission circuits, which typically operate at higher voltages (e.g.,up to 1,100 kV). Reclosers allow for multiple automated attempts toclear temporary faults on overhead lines. In power transmission systems,this function is typically achieved using circuit breakers insubstations. The present disclosure provides switchgear in the form of arecloser that can operate at voltages up to 72.5 kV. In someembodiments, the switchgear according to the present disclosure includesa vacuum interrupter assembly with a vacuum bottle and a sleeve over thevacuum bottle that allows for a more consistent seal when molding adielectric material about the vacuum interrupter assembly (i.e., anovermold).

By providing a more consistent overmold, the present disclosureadvantageously provides better over-current protection with reduceddegradation over time, which provides better protection against arcingover the contacts of the vacuum interrupter. For example, the sleeve mayhelp keep the dielectric material used in an overmolding process fromentering gaps and/or cracks that may be present within and/or betweencomponents of the vacuum assembly. This reduces the number of customersor end users impacted by a potential fault and therefore improves thepower transmission system's reliability.

The present disclosure provides, in one aspect, a switchgear apparatusconfigured for operation at voltages up to 72.5 kV, the switchgearapparatus including a vacuum interrupter assembly including a vacuumbottle having an upper portion and a lower potion, a sleeve surroundingthe vacuum bottle, a dielectric material surrounding the sleeve, a firstterminal electrically coupled to the upper portion of the vacuuminterrupter assembly, and an interchange coupled to a lower portion ofthe vacuum interrupter assembly. The dielectric material is moldedaround the sleeve and around at least a portion of the first terminal orthe interchange. In some embodiments, the sleeve is molded around thevacuum bottle. In other embodiments, the sleeve may be otherwisepositioned (i.e., by sliding a pre-formed sleeve) around the vacuumbottle.

The present disclosure provides, in another aspect, a switchgearapparatus configured for operation at voltages up to 72.5 kV, theswitchgear apparatus including a vacuum interrupter assembly including avacuum bottle having an upper portion and a lower potion, and a fixedcontact and a movable contact hermetically sealed within the vacuumbottle. The switchgear apparatus further includes a first terminalelectrically coupled to fixed contact at the upper portion of the vacuumbottle, an interchange coupled to the movable contact at the lowerportion of the vacuum bottle, a conductor electrically coupled to theinterchange, a second terminal electrically coupled to the conductor,and a sensor assembly associated with the conductor. The sensor assemblyincludes at least one of a voltage sensor or a current sensor. Anactuator assembly is operable to selectively break a conductive pathwaybetween the first terminal and the second terminal by moving the movablecontact from a closed position in which the movable contact engages thefixed contact to an open position in which the movable contact is spacedfrom the fixed contact. The actuator assembly includes a drive shaftconfigured to move the movable contact between the closed position andthe open position, a magnet configured to maintain the drive shaft in aposition corresponding with the closed position of the movable contact,and a dielectric material molded around the vacuum interrupter assembly.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a recloser and/or switchgearapparatus (“recloser”) according to an embodiment of the presentdisclosure.

FIG. 2 illustrates a cross-sectional view of the recloser of FIG. 1.

FIG. 3 illustrates a detailed, cross-sectional view of a top portion ofthe vacuum interrupter assembly of the recloser of FIG. 1.

FIG. 4 illustrates a detailed, cross-sectional view of a bottom portionof the vacuum interrupter assembly of the recloser of FIG. 1.

DETAILED DESCRIPTION

Before any embodiments of the disclosure are explained in detail, it isto be understood that the disclosure is not limited in its applicationto the details of construction and the arrangement of components setforth in the following description or illustrated in the followingdrawings. The disclosure is capable of supporting other embodiments andof being practiced or of being carried out in various ways. Also, it isto be understood that the phraseology and terminology used herein is forthe purpose of description and should not be regarded as limiting. Also,as used herein and in the appended claims, the terms “upper,” “lower,”“top,” “bottom,” “front,” “back,” and other directional terms are notintended to require any particular orientation, but are instead used forpurposes of description only.

FIG. 1 illustrates a recloser 10 according to an embodiment of thepresent disclosure. The recloser 10 includes a housing assembly 14, avacuum interrupter (“VI”) assembly 18, a conductor assembly 22, which insome embodiments may be a load-side conductor assembly 22 and in otherembodiments may be a source-side conductor assembly 22, and an actuatorassembly 26. The VI assembly 18 includes a first terminal 30 extendingfrom the housing assembly 14 along a first longitudinal axis 34, and theconductor assembly 22 includes a second terminal 38 extending from thehousing assembly 14 along a second longitudinal axis 42 perpendicular tothe first longitudinal axis 34. In other embodiments, the secondlongitudinal axis 42 may be obliquely oriented relative to the firstlongitudinal axis 34. The actuator assembly 26 may operate the VIassembly 18 to selectively break and/or reestablish a conductive pathwaybetween the first and second terminals 30, 38. Although the recloser 10is illustrated individually in FIG. 1, the recloser 10 may be part of arecloser system including a plurality of reclosers 10, each associatedwith a different phase of a three-phase power transmission system andganged together such that operation of the plurality of reclosers 10 issynchronized.

Referring now to FIG. 2, the illustrated housing assembly 14 includes amain housing 46 with an insulating material, such as epoxy, that forms asolid dielectric module 47. The solid dielectric module 47 is preferablymade of a silicone or cycloaliphatic epoxy. In other embodiments, thesolid dielectric module 47 may be made of a fiberglass molding compound.In other embodiments, the solid dielectric module 47 may be made ofother moldable dielectric materials. The main housing 46 may furtherinclude a protective layer 48 surrounding the solid dielectric module47. In some embodiments, the protective layer 48 withstands heavilypolluted environments and serves as an additional dielectric materialfor the recloser 10. In some embodiments, the protective layer 48 ismade of silicone rubber that is overmolded onto the solid dielectricmodule 47. In other embodiments, the protective layer 48 may be made ofother moldable (and preferably resilient) dielectric materials, such aspolyurethane.

With continued reference to FIG. 2, the main housing 46 includes a firstbushing 50 that surrounds and at least partially encapsulates the VIassembly 18, and a second bushing 54 that surrounds and at leastpartially encapsulates the conductor assembly 22. The silicone rubberlayer 48 includes a plurality of sheds 58 extending radially outwardfrom both bushings 50, 54. In other embodiments, the sheds 58 may beformed as part of the dielectric module 47 and covered by the siliconerubber layer 48. In yet other embodiments, the sheds 58 may be omitted.The first and second bushings 50, 54 may be integrally formed togetherwith the dielectric module 47 of the main housing 46 as a singlemonolithic structure. Alternatively, the first and second bushings 50,54 may be formed separately and coupled to the main housing 46 in avariety of ways (e.g., via a threaded connection, snap-fit, etc.).

The illustrated VI assembly 18 includes a vacuum bottle 62 at leastpartially molded within the first bushing 50 of the main housing 46. Insome embodiments, the vacuum bottle 62 is additionally or alternativelypressed into the first bushing 50 of the main housing 46. In someembodiments, the vacuum bottle 62 is surrounded by a sleeve 158, whichis preferably made of a resilient dielectric material such as siliconerubber. The vacuum bottle 62 encloses a movable contact 66 and astationary contact 70 such that the movable contact 66 and thestationary contact 70 are hermetically sealed within the vacuum bottle62. The movable contact 66 is maintained in contact with an interchange82 through the use of contact bands. Contact between the moveablecontact 66 and the interchange 82 may be maintained through frictionalcontact. In some embodiments, (i) the sleeve 158 is molded around the VIassembly 18, and includes silicone, (ii) the solid dielectric module 47is molded around the sleeve 158, and includes an epoxy, and (iii) thesilicone rubber layer 48 is molded around the solid dielectric module47, and includes silicone. Such an embodiment including each of (i) to(iii) may be particularly advantageous in a high voltage (i.e., 72.5 kV)recloser to establish or break electrical contact within the VI assembly18 because of the more consistent molding process provided by each ofthe overmolds (i) to (iii).

In some embodiments, the vacuum bottle 62 has an internal absolutepressure of about 1 millipascal or less. The movable contact 66 ismovable along the first longitudinal axis 34 between a closed position(illustrated in FIG. 2) and an open position (not shown) to selectivelyestablish or break contact with the stationary contact 70. The vacuumbottle 62 quickly suppresses electrical arcing, for example suppressionmay occur in less than 30 milliseconds, that may occur when the contacts66, 70 are opened due to the lack of conductive atmosphere within thebottle 62. In some embodiments, the vacuum bottle 62 suppresseselectrical arcing in a time of between about 8 milliseconds and about 30milliseconds.

The conductor assembly 22 may include a conductor 74 and a sensorassembly 78, each at least partially molded within the second bushing 54of the main housing 46. The sensor assembly 78 may include a currentsensor, a voltage sensor, partial discharge sensor, voltage indicatedsensor, and/or other sensing devices. One end of the conductor 74 iselectrically coupled to the movable contact 66 via the currentinterchange 82. The opposite end of the conductor 74 is electricallycoupled to the second terminal 38. The first terminal 30 is electricallycoupled to the stationary contact 70. The first terminal 30 and thesecond terminal 38 are configured for connection to respectiveelectrical power transmission lines.

With continued reference to FIG. 2, the actuator assembly 26 includes adrive shaft 86 extending through the main housing 46 and coupled at oneend to the movable contact 66 of the VI assembly 18. In the illustratedembodiment, the drive shaft 86 is coupled to the movable contact 66 viaan encapsulated spring 90 to permit limited relative movement betweenthe drive shaft 86 and the movable contact 66. The encapsulated spring90 biases the movable contact 66 toward the stationary contact 70. Theopposite end of the drive shaft 86 is coupled to an output shaft 94 ofan electromagnetic actuator 98. The electromagnetic actuator 98 isoperable to move the drive shaft 86 along the first longitudinal axis 34and thereby move the movable contact 66 relative to the stationarycontact 70. In additional or alternative embodiments, the functionalityprovided by the encapsulated spring 90 may be provided with an externalspring and/or a spring positioned otherwise along the drive shaft 86.For example, the spring may be instead positioned at a first end or at asecond end of the drive shaft 86.

The electromagnetic actuator 98 in the illustrated embodiment includes acoil 99, a permanent magnet 100, and a spring 101. The coil 99 includesone or more copper windings which, when energized, produce a magneticfield that acts on the output shaft 94. The permanent magnet 100 isconfigured to hold the output shaft 94 in a position corresponding withthe closed position of the movable contact 66. The spring 101 biases theoutput shaft 94 in an opening direction (i.e. downward in theorientation of FIG. 2). In some embodiments, the actuator assembly 26may include other actuator configurations. For example, in someembodiments, the permanent magnet 100 may be omitted, and the outputshaft 94 may be latched in the closed position in other ways. Inadditional or alternative embodiments, the electromagnetic actuator 98may be omitted.

The actuator assembly 26 includes a controller (not shown) that controlsoperation of the electromagnetic actuator 98. In some embodiments, thecontroller receives feedback from the sensor assembly 78 and energizesor de-energizes the electromagnetic actuator 98 in response to one ormore sensed conditions. For example, the controller may receive feedbackfrom the sensor assembly 78 indicating that a fault has occurred. Inresponse, the controller may control the electromagnetic actuator 98 toautomatically open the VI assembly 18 and break the circuit. Thecontroller may also control the electromagnetic actuator 98 toautomatically close the VI assembly 18 once the fault has been cleared(e.g., as indicated by the sensor assembly 78).

In the exemplary illustrated embodiment, the actuator assembly 26further includes a manual trip assembly 102 that can be used to manuallyopen the VI assembly 18 through the operation of the drive shaft 86and/or other linkages. The manual trip assembly 102 includes a handle104 accessible from an exterior of the housing assembly 14 (as shown inFIG. 1). The handle 104 is rotatable to move a yoke 106 inside thehousing assembly 14 (as shown in FIG. 2). The yoke 106 is engageablewith a collar 110 on the output shaft 94 to move the movable contact 66toward the open position. The illustrated housing assembly 14 includesan actuator housing 114 enclosing the electromagnetic actuator 98 and ahead casting 118 coupled between the actuator housing 114 and the mainhousing 46. The manual trip assembly 102 is supported by the headcasting 118, and the output shaft 94 extends through the head casting118 to the drive shaft 86.

Referring now to FIG. 3, a detailed, cross-sectional view of a topportion of the VI assembly 18 of the recloser 10 is shown. The sleeve158 is shown positioned around the vacuum bottle 62. The first terminal30 is seated against the sleeve 158 at an upper connection point 151within the first bushing 50. The sleeve 158 is compressed between thefirst terminal 30 and the top of the vacuum bottle 62 to form a completeseal between the first terminal 30 and the vacuum bottle 62. In theillustrated embodiment, the upper connection point 151 between the firstterminal 30 and the sleeve 158 is completely molded (i.e., entirelysurrounded in molding) within dielectric material 152 of the dielectricmodule 47 (cross-hatching of the dielectric material 152 is omitted fromFIG. 3 for the purpose of more clearly illustrating the sleeve 158). Inother words, the upper connection point 151 is entirely encapsulated bythe dielectric material 152.

In additional and/or alternative embodiments, a method related to thestructure disclosed herein may include providing the vacuum bottle 62and the first terminal 30, positioning the sleeve 158 about the vacuumbottle 62, positioning the first terminal 30 against a portion of thesleeve 158 surrounding an opening of the vacuum bottle 62, andcompressing the portion of the sleeve 158 between the first terminal 30and the vacuum bottle 62 to form a seal between the first terminal 30and the vacuum bottle 62. A contact area between the sleeve 158 and thefirst terminal 30 is the upper connection point 151. The method mayfurther include encapsulating at least the upper connection point 151 bymolding the dielectric material 152 over at least the upper connectionpoint 151. Such a configuration and/or method may advantageously inhibitcreepage and tracking from the VI assembly 18. In some embodiments, thesleeve 158 may be compressed before, during, and/or after molding thedielectric material 152.

Referring now to FIG. 4, a detailed, cross-sectional view of a bottomportion of the VI assembly 18 of the recloser 10 of FIG. 1 isillustrated. As shown, the interchange 82 is positioned to interact withan interchange terminal 153 along the first longitudinal axis 34 (andconfigured to connect to the movable contact 66, shown in FIG. 2) andthe connector 74 along the second longitudinal axis 42. The interchange82 connects to the sleeve 158 positioned about the vacuum bottle 62 at alower connection point 156.

In the illustrated embodiment, the sleeve 158 includes at least oneridge 157 integrally formed with the sleeve 158 and surrounding thecircumference of the sleeve 158 at the lower connection point 156. Theinterchange 82 may include a mating feature (e.g., one or more ridges,grooves, or the like) configured to cooperate with the ridge 157 on thesleeve 158 to form a seal between the vacuum bottle 62 and theinterchange 82 at the lower connection point 156. In the illustratedembodiment, the lower connection point 156 is completely molded (i.e.,entirely surrounded in molding) with the dielectric material 152(cross-hatching of the dielectric material 152 is again omitted fromFIG. 4 for the purpose of clarity). In other words, the lower connectionpoint 156 is entirely encapsulated by the dielectric material 152.

For example, in additional and/or alternative preferred embodiments, amethod related to the structure disclosed herein may include providingthe vacuum bottle 62 within the sleeve 158 and the interchange 82,positioning a portion of the sleeve 158 around an opening of the vacuumbottle 62 against and/or partially within the interchange 82 such thatthe ridge 157 is located between the sleeve 158 and the interchange 82,and molding the dielectric material 152 over the sleeve 158 and theinterchange 82. Such a configuration and/or method may advantageouslyprevent the dielectric material 152 (e.g., epoxy) from leaking into theconnection between the vacuum bottle 62 and the interchange 82 duringmolding. In addition, by sealing between the vacuum bottle 62 and theinterchange 82, the sleeve 158 may also inhibit creepage and trackingfrom the VI assembly 18 at the lower connection point 156.

An exemplary operating sequence of the recloser 10 according to certainembodiments of the present disclosure will now be described withreference to FIG. 2. During operation, the controller of the recloser 10may receive feedback from the sensor assembly 78 indicating that a faulthas occurred. In response to this feedback, the controller automaticallyenergizes the coil 99 of the electromagnetic actuator 98. The resultantmagnetic field generated by the coil 99 moves the output shaft 94 in anopening direction (i.e. downward in the orientation of FIG. 2). Thismovement creates an air gap between the output shaft 94 and thepermanent magnet 100 that greatly reduces the holding force of thepermanent magnet 100. With the holding force of the permanent magnet 100reduced, the spring 101 is able to overcome the holding force of thepermanent magnet 100 and accelerate the output shaft 94 in the openingdirection. As such, the coil 99 is only required to be energizedmomentarily to initiate movement of the output shaft 94, advantageouslyreducing the power drawn by the electromagnetic actuator 98 andminimizing heating of the coil 99.

The output shaft 94 moves the drive shaft 86 in the opening direction.As the drive shaft 86 moves in the opening direction, the encapsulatedspring 90, which is compressed when the contacts 66, 70 are closed,begins to expand. The spring 90 thus initially permits the drive shaft86 to move in the opening direction relative to the movable contact 66and maintains the movable contact 66 in fixed electrical contact withthe stationary contact 70. As the drive shaft 86 continues to move andaccelerate in the opening direction under the influence of the spring101, the spring 90 reaches a fully expanded state. When the spring 90reaches the fully expanded state, the downward movement of the driveshaft 86 is abruptly transferred to the movable contact 66. Thisseparates the movable contact 66 from the stationary contact 70 andreduces arcing that may occur upon separating the contacts 66, 70. Themovable contact may be separated in a time of between 8 milliseconds and30 milliseconds. By quickly separating the contacts 66, 70, degradationof contacts 66, 70 due to arcing is reduced, and the reliability of theVI assembly 18 is improved.

Thus, the present disclosure provides a high voltage recloser 10suitable for use in power transmission applications up to 72.5 kV. TheVI assembly 18 quickly and reliably suppresses arcing without the needfor an oil tank or a gas-filled container containing sulphurhexafluoride (SF6), which is a potent greenhouse gas. In addition, theVI assembly 18 disclosed herein is advantageously maintenance free.

Various features and advantages of the invention are set forth in thefollowing claims.

What is claimed is:
 1. A switchgear apparatus configured for operationat voltages up to 72.5 kV, the switchgear apparatus comprising: a vacuuminterrupter assembly including a vacuum bottle having an upper portionand a lower potion; a sleeve surrounding the vacuum bottle; a dielectricmaterial surrounding the sleeve; a first terminal electrically coupledto the upper portion of the vacuum bottle; and an interchange coupled tothe lower portion of the vacuum bottle, wherein the dielectric materialis molded around the sleeve and around at least a portion of the firstterminal or the interchange.
 2. The switchgear apparatus of claim 1,wherein the dielectric material is molded around the sleeve, at least aportion of the first terminal, and at least a portion of theinterchange.
 3. The switchgear apparatus of claim 1, wherein the sleeveis compressed between the first terminal and the upper portion of thevacuum bottle.
 4. The switchgear apparatus of claim 1, wherein thesleeve includes a ridge that forms a seal between the interchange andthe lower portion of the vacuum bottle.
 5. The switchgear apparatus ofclaim 1, wherein the sleeve comprises silicone rubber.
 6. The switchgearapparatus of claim 1, wherein the dielectric material comprises epoxy.7. The switchgear apparatus of claim 6, wherein the dielectric materialcomprises silicone epoxy.
 8. The switchgear apparatus of claim 1,further comprising a protective layer surrounding the dielectricmaterial.
 9. The switchgear apparatus of claim 8, wherein the protectivelayer comprises silicone rubber.
 10. The switchgear apparatus of claim1, wherein the protective layer comprises a plurality of sheds.
 11. Theswitchgear apparatus of claim 1, wherein the vacuum interrupter assemblyincludes a fixed contact electrically coupled to the first terminal anda movable contact electrically coupled to the second terminal.
 12. Theswitchgear apparatus of claim 11, further comprising an actuatorassembly operable to selectively break a conductive pathway between thefirst terminal and the second terminal by moving the movable contactaway from the fixed contact.
 13. The switchgear apparatus of claim 12,wherein the actuator assembly includes an electromagnetic actuator. 14.The switchgear apparatus of claim 12, wherein the actuator assemblyincludes a spring actuator.
 15. The switchgear apparatus of claim 12,wherein: the movable contact is movable between a closed position inwhich the movable contact is in electrical contact with the fixedcontact and an open position in which the movable contact is spaced fromthe fixed contact, the actuator assembly includes a drive shaftconfigured to move the movable contact between the closed position andthe open position, and the actuator assembly further includes a magnetconfigured to maintain the drive shaft in a position corresponding withthe closed position of the movable contact.
 16. The switchgear apparatusof claim 1, further comprising a conductor electrically coupled to theinterchange and a sensor assembly associated with the conductor, whereinthe sensor assembly includes at least one of a voltage sensor or acurrent sensor, and wherein the sensor assembly is molded within thedielectric material.
 17. A switchgear apparatus configured for operationat voltages up to 72.5 kV, the switchgear apparatus comprising: a vacuuminterrupter assembly including a vacuum bottle having an upper portionand a lower potion, and a fixed contact and a movable contacthermetically sealed within the vacuum bottle; a first terminalelectrically coupled to fixed contact at the upper portion of the vacuumbottle; an interchange coupled to the movable contact at the lowerportion of the vacuum bottle; a conductor electrically coupled to theinterchange; a second terminal electrically coupled to the conductor; asensor assembly associated with the conductor, wherein the sensorassembly includes at least one of a voltage sensor or a current sensor;an actuator assembly operable to selectively break a conductive pathwaybetween the first terminal and the second terminal by moving the movablecontact from a closed position in which the movable contact engages thefixed contact to an open position in which the movable contact is spacedfrom the fixed contact, wherein the actuator assembly includes a driveshaft configured to move the movable contact between the closed positionand the open position, and a magnet configured to maintain the driveshaft in a position corresponding with the closed position of themovable contact; and a dielectric material molded around the vacuuminterrupter assembly.
 18. The switchgear of claim 17, wherein the sensorassembly is molded within the dielectric material.
 19. The switchgear ofclaim 18, wherein the conductor, the interchange, and at least a portionof the first terminal are molded within the dielectric material.
 20. Theswitchgear of claim 17, further comprising a sleeve made of siliconerubber disposed between at least a portion of the vacuum interrupterassembly and the dielectric material.